Another 99 Cobra build thread...

Slammed99Vert

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Guys tell me if you don’t want to read this and I’ll document it off record. Lol. I’ve been a member for a little while and kept an eye on this forum for years quietly taking advice where I can find it for my mustangs over the years. I’ve had and sold a few over the years. Starting with a v6 new edge years ago then moving into a couple of gts, a bullitt, and now the gt that is my wife’s baby and my 99 cobra. What can I say, we like the New Edge. We also like our verts. Both of the cars we have now are convertibles. Anyway, on to the meat and potatoes here. Ever since I bought the Cobra it’s had some cold start piston slap and burns some oil. Nothing extreme, but relatively annoying. Also, it stops me from adding any power adders to the car. Blowby is evident in the three pcv’s I’ve replaced. The previous owner swore it had been forged at some point and I put some 98 Cobra intake cams on her along with some of your more common boltons. Once warm she runs strong for a n/a 99 Cobra. Not saying much I know but still. The t-45 is as strong as it can be with full hd build kit from Stan and a very fresh rebuild. Other than the gears in the back, the car is mostly stock with some lowering “performance” springs. She handles okay, but let’s just say she isn’t setting any records. I got the car for a really good price and the body is perfectly straight with the exception of the bumper covers which have taken some road and parking lot bumps. Namely the rear cover that has been “bumped” twice now by people on their damn phones! She has been my daily work driver(I’m an insurance inspector/investigator, lots of miles!)for 2 years now and it’s come time to retire her to the garage for a full rebuild and mainly track duty and weekend SoCal top down driving after that. So far the build list consists of a full motor rebuild by yours truly(with the exception of machine work). I’m hoping that the rods at least have been replaced with decent forged rods as the previous own said they had, but the pistons are likely going to need to be replaced. I assume the slapping is coming from improper sized pistons to the bore, and that they haven’t done too much damage to the walls. Maybe I’ll get lucky and it’s a piston ring issue? Chime in on anything that makes me sound like a noob please and thank you! Sound criticism will only make my car better in the long run! Any how, as it looks most of the motor rebuild is dependent on what it looks like after we pull the bullet and crack her open. In the chance that it hasn’t actually been forged I was thinking of 03-04 Cobra rods and Manley 11cc dished pistons to fit whatever bore we end up with after figuring out if the walls need to be cleaned. The plan is for a conservative 600 rwhp motor on twins. Obviously dish size will be dependent on how big the bore goes to make sure compression doesn’t dip too low. Any thoughts on my above listed build will be GREATLY appreciated! Also anyone’s thoughts on sleeving the motor are also massively welcome! My thoughts are that it shouldn’t be necessary for the amount of hp I’m looking to make, but if I’m wrong please correct me! Moving back, as I said the transmission has had the full treatment including the 26 spline input shaft, billet forks, brass pads, carbon synchros, mgw shifter blablabla. So for the time being we will see how it holds up after power is added. Further back as I mentioned it has gears but it still has the stock 99 rear end. So only 26 spline half shafts. I’ve been debating on looking for a 03-04 31 spline rear but I’m not sure it’s going to be needed considering this car won’t be on any drag duty, mainly road course, small autocross, and SoCal canyons on the weekends. Once again if I am mistaken please correct me! Suspension wise(even though it’s a ways out for now) will be a full front and rear maximum grip box all the way around. Pricey I know, but I don’t know of any other proven options that would be any less money. Suspension on this car is where I would need the most input I think guys so help and pointers would be awesome! Here’s a picture of how my girl sits now. I’ll be posting as things progress throughout the build. It’s not going to be a rush job I want it done right and I want to do it myself. Massive learning curve I know but I’m pretty handy and I’ll be taking as much time as needed to do it right the first time! Pointers, tips, critiques, and any advice is welcome during the entire process! Like I said, sound criticism will only help make my car better! Thanks for your time here guys! And I look forward to any and all help!
 

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shurur

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please don't be offended that I broke your post up a bit to make it more legible.
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888888888888888888888888888888888888888888888888888888
Guys tell me if you don’t want to read this and I’ll document it off record.

Lol. I’ve been a member for a little while and kept an eye on this forum for years quietly taking advice where I can find it for my mustangs over the years. I’ve had and sold a few over the years. Starting with a v6 new edge years ago then moving into a couple of gts, a bullitt, and now the gt that is my wife’s baby and my 99 cobra.

What can I say, we like the New Edge. We also like our verts. Both of the cars we have now are convertibles.

Anyway, on to the meat and potatoes here.

Ever since I bought the Cobra it’s had some cold start piston slap and burns some oil. Nothing extreme, but relatively annoying; however, it stops me from adding any power adders to the car. Blowby is evident in the three pcv’s I’ve replaced.

The previous owner swore it had been forged at some point and I put some 98 Cobra intake cams on her along with some of your more common boltons.

Once warm she runs strong for a n/a 99 Cobra. That’s not saying much, I know, but still.

The t-45 is as strong as it can be with full hd build kit from Stan and a very fresh rebuild.

Other than the gears in the back, the car is mostly stock with some lowering “performance” springs. She handles okay, but let’s just say she isn’t setting any records.

I got the car for a really good price and the body is perfectly straight with the exception of the bumper covers which have taken some road and parking lot bumps. Namely the rear cover that has been “bumped” twice now by people on their damn phones!

She has been my daily work driver(I’m an insurance inspector/investigator, lots of miles!)for 2 years now and it’s come time to retire her to the garage for a full rebuild and mainly track duty and weekend SoCal top down driving after that.

So far the build list consists of a full motor rebuild by yours truly(with the exception of machine work). I’m hoping that the rods at least have been replaced with decent forged rods as the previous own said they had, but the pistons are likely going to need to be replaced. I assume the slapping is coming from improper sized pistons to the bore, and that they haven’t done too much damage to the walls. Maybe I’ll get lucky and it’s a piston ring issue?

Chime in on anything that makes me sound like a noob please and thank you!

Sound criticism will only make my car better in the long run! Any how, as it looks most of the motor rebuild is dependent on what it looks like after we pull the bullet and crack her open. In the chance that it hasn’t actually been forged I was thinking of 03-04 Cobra rods and Manley 11cc dished pistons to fit whatever bore we end up with after figuring out if the walls need to be cleaned.

The plan is for a conservative 600 rwhp motor on twins.

Obviously dish size will be dependent on how big the bore goes to make sure compression doesn’t dip too low.

Any thoughts on my above listed build will be GREATLY appreciated!

Also anyone’s thoughts on sleeving the motor are also massively welcome! My thoughts are that it shouldn’t be necessary for the amount of hp I’m looking to make, but if I’m wrong please correct me!

Moving back, as I said the transmission has had the full treatment including the 26 spline input shaft, billet forks, brass pads, carbon synchros, mgw shifter blablabla. So for the time being we will see how it holds up after power is added.

Further back as I mentioned it has gears but it still has the stock 99 rear end. So only 26 spline half shafts. I’ve been debating on looking for a 03-04 31 spline rear but I’m not sure it’s going to be needed considering this car won’t be on any drag duty, mainly road course, small autocross, and SoCal canyons on the weekends.

Once again if I am mistaken please correct me!

Suspension wise(even though it’s a ways out for now) will be a full front and rear maximum grip box all the way around. Pricey I know, but I don’t know of any other proven options that would be any less money.

Suspension on this car is where I would need the most input, I think guys; so help and pointers would be awesome!

Here’s a picture of how my girl sits now. I’ll be posting as things progress throughout the build. It’s not going to be a rush job I want it done right and I want to do it myself. Massive learning curve I know but I’m pretty handy and I’ll be taking as much time as needed to do it right the first time!

Pointers, tips, critiques, and any advice is welcome during the entire process! Like I said, sound criticism will only help make my car better! Thanks for your time here guys! And I look forward to any and all help!
 

dhoening

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The ‘99 (and I think ‘01) blocks have the first version of the spray-bore technology. So I don’t think you will be boring this block. That also means sleeving may not be possible (although I’m not an expert on that aspect). Good luck.
 

Slammed99Vert

“Ouch” the story of my life...
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The ‘99 (and I think ‘01) blocks have the first version of the spray-bore technology. So I don’t think you will be boring this block. That also means sleeving may not be possible (although I’m not an expert on that aspect). Good luck.

It is a Teksid block if that make a difference. But I could have swore I’ve read about guys boring .030 over, whether it be for displacement or cylinder wall issues. I guess I’ll start digging! Lol thanks for the heads up!
 

Slammed99Vert

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So from what I’m finding .020 is the biggest you want to go for boosted applications unless you sleeve on the aluminum block. Some input on this would be great from someone that’s been there and done that lol.
 

01yellercobra

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The ‘99 (and I think ‘01) blocks have the first version of the spray-bore technology. So I don’t think you will be boring this block. That also means sleeving may not be possible (although I’m not an expert on that aspect). Good luck.
That's a negative. The Teksid and WAP blocks are sleeved. I had a big bore Teksid. But it ended up with cracks due to improper machining. IMO if you want a big bore set up get a Boss block. Less headache in the long run.

If you only want 600 you don't need a lot. Cleaned up heads and a decent short block will get you there. Once you get the engine apart you can make more decisions.

Ideally you want the least amount of material removed. So if you can clean it up with .010" go with that. I'd say .020" is max. Most builders will tell you if the block needs more its time to find a new block.

FWIW my Boss block set up made 500rwhp on a Mustang dyno with low boost and no timing. That was with stock heads, intake, and Ford GT cams.

The 99 IRS has 28 spline inner shafts, not 26. I would look into upgrading to 03/04 shafts and diff at the very least. I grenaded a stock 01 shaft on a hard shift getting on the freeway.
 
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Slammed99Vert

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Right, duh! Sorry, had my input shaft spline count confused with my half shafts @slo984now. Thanks for the info! I’m not planning on going to big with it. Honestly like you said as little as I can get away with, if the cylinder walls need it at all preferably. Excuse my ignorance but will my 4v heads fit on the boss block? If the Teksid is spent that may be an option. REALLY hoping it’s not lol. As far as the rear is concerned, that sounds like absolutely HORRID luck bro! Sorry to hear that. But in that case I will be on the lookout for a full 03-04 rear from someone that did a SRA swap. Hell, maybe I’ll give my wife my irs for her gt. Any takers on a gt sra trade for a full 03-04 rear?
 

01yellercobra

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All of the heads will bolt onto the Boss block. I knew a guy that built a 3V with that engine. It all depends on the pistons. You need the correct pistons to clear the valves.

I knew I was on borrowed time with the IRS. I had the big bore stroker with a D1 at the time. So I was roughly double the stock power output. And I was on drag radials.

You don't need the whole IRS. Pick up a 31 spline diff and 03/04 axles and you'll be good. Those with some good bushings will set you up.
 

scottydsntknow

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Clean up your stock heads, hone or .010 over on your block, use your OEM Kellogg forged crank, Boss rods from Tasca or Autonation for $200, your choice of pistons for $550-$750. Boring and stroking these engines is asinine if its just a street car. Completely unecessary. Put it all together, degree/advance the stock cams, bolt together with OEM hardware/gaskets and then boost it. There you go for 600 reliable. I'd be more concerned about the trans and rear. IRS needs a full going through and upgrade to 03/04 diff/axles. Trans is a T45 and those aren't great... swap to a fresh 3650 with a 26 spline or a Magnum or swap to an automatic 6R80.
 

98_Undertaker

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I work in a machine shop and I would recommend going at least .010 over. I wouldn’t bother with trying a stock bore size, I also highly recommend torque plating we only bore and hone with torque plates on the 4.6/5.4 and coyotes. We bored a teksid .020 over I’ve heard of people going .060 over but that would be pushing it very thin on the stock sleeves.

As far as connecting rods go you can use boss rods as a cheap alternative but remember it’s still a stock rod all be it a fairly stout stock rod. 03/04 manleys are a good choice but more expensive and they already come with arp 8740 bolts.

Pistons we use either Mahle, CP, Manley, or have them custom built by racetec.

As said above me don’t forget about the rest of the drivetrain.


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wraitherlx

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I had my teksid, when I owned it, .030 over. The key to the reliability in that is ensuring the machinist uses torque plates. I got rid of it 3 years after my build with a couple of runs through the track, driving for long periods, stop and go traffic in the dead of summer with the AC on high, and never had issues. Some have done it and had issues with hairline cracks and overheating. But I’ve never had an issue with the build whatsoever.


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Ironmancuck

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I wouldn’t even do a .010 hone because I want the thickest walls possible in order for them to survive under boost. I would also skip the boss rods and at minimum use the Manley H beams. Hone only enough to remove any taper and then order custom pistons to match.
 

Slammed99Vert

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Guys thanks for all the input it really means a TON! With any luck and little to no rain tomorrow the motor should be coming out or at least starting to come out tomorrow! I’m excited and nervous lol. As soon as it’s out and we’ve got it on a stand (maybe after a beer or two to get ready for the inevitable disappointment in the original owners “word”) I’ll post some pictures up and we can start to come up with a game plan lol.

@scottydsntknow Correct me if I am mistaken, but I’ve always been under the assumption that a built t45 is slightly more stout than a built tr3650. Had one built the same way my t45 is now, all parts from Stan, in a 04 gt and it never seemed quite as robust. Mind you, I never had any real issues with that tr3650, but the built t45 I have now just seems to, at very minimum grab the gears harder with a much more positive engagement feeling when I’m really hammering on it. I know the stock numbers for each definitely show favor to the tr3650, but as I said I was always under the impression a built t45 could handle just a little more.
 

scottydsntknow

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3650 OEM gears are stronger, 3650 also has aftermarket gearsets which can take a crapton more than any t45 gears can.

I mean if you have a built t45 then roll with that but I wouldn't run one past 600hp.

The biggest issue with t45s these days is parts availability, there is really 0 aftermarket for it. That's exactly what it says on Stan's page too.

Rebuilt T-45 Transmissions in Atlanta Georgia
 

01yellercobra

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IMO you should consider a six speed. I know you have the built T-45, but I think the T-56 is a big step up. I went from the 3650 to the T-56 in my 01 and liked it a lot better. The gear spacing makes things easier to drive. If you can swing it I'm pretty sure the Magnum would take anything you can throw at it. I haven't shifted one personally, but everyone that switches to the Magnums says they shift like butter.
 

Slammed99Vert

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Money permitting the magnum is what I want. Maybe I can get lucky with a junk yard pull? What else would I need to pull off that car to make it work in the 99? Other than a custom drive shaft. I know parts are scarce for the t45 but it’s what I’ve got on hand as of now. It’s in really good shape internally and it’s as built as a t45 can be.

Couldn’t get nearly as much finished today as I wanted so no pics today. This is all pretty new to me so bare with me. I am doing this out of my buddies shop in the mountains where I live, so we don’t have a full lift so the motor has to come out the top. Any advice or tips for doing that?
 
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Brutal Metal

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Clean up your stock heads, hone or .010 over on your block, use your OEM Kellogg forged crank, Boss rods from Tasca or Autonation for $200, your choice of pistons for $550-$750. Boring and stroking these engines is asinine if its just a street car. Completely unecessary. Put it all together, degree/advance the stock cams, bolt together with OEM hardware/gaskets and then boost it. There you go for 600 reliable. I'd be more concerned about the trans and rear. IRS needs a full going through and upgrade to 03/04 diff/axles. Trans is a T45 and those aren't great... swap to a fresh 3650 with a 26 spline or a Magnum or swap to an automatic 6R80.
600 on his build with how much boost? A LOT with 93 pump to achieve that #.. My T-45 has held up fine.. same with the oem 28 spline half shafts but I'm not stupid launching at 5K, I know it's weak. I'll leave and 2K and ride the clutch out on the launch to avoid shocking the rear.
 

Brutal Metal

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I wouldn’t even do a .010 hone because I want the thickest walls possible in order for them to survive under boost. I would also skip the boss rods and at minimum use the Manley H beams. Hone only enough to remove any taper and then order custom pistons to match.
You do realize that all the major piston companies have .020 and .030 over offerings? My Teksid block is .020.
 

scottydsntknow

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Honestly if this is anything but a handling car, put a 6R80 in it. Bone stock trans is a monster as is, don't have to do shit to it.
 

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